I am not certain whether the motherboard is related, but I know that the AGP support (which GART deals with) is not the sole cause of the problem; the problem still occurs with it disabled. The FX5200 is old enough you can probably safely use 4363 (if it doesn't work you can always go back to the latest release). With a 2.4 kernel, just use the normal download from the archive. Minion.de is a site that releases drivers patched for kernel 2.6, it is not relevant to 2.4. It is the only source I am aware of for kernel 2.6 compatible versions of old drivers.

You only really need the nVidia drivers for OpenGL 3D support (you have to use software rendering with the nv drivers for 3D, which is extremely slow.) For other uses, nv drivers should be fine.